Light Fixtures
Airport Lights
Light Fixture 3
Airfields equipped for low visibility operations use lights to provide visual guidance to pilots for takeoff, landing and taxiing. Lights are usually at the edge of paved areas or embedded in paved areas. Those embedded in the pavement area usually flush with the final pavement surface and can be difficult to pave around.
Individual Lights
Light fixtures (see Image) that are spaced far apart so that each fixture is an individual unit (e.g., runway centerline lights) can generally be paved over by placing the fixture, fitting the fixture with a sacrificial cover (e.g., plywood cut to shape), and locating the fixture with a global positioning system (GPS) device. Once located, the light fixtures can be paved over and then later precisely located using the recorded GPS coordinates and cored to expose the fixture. The light can then be installed and shimmed up to the proper elevation.
Light Groups
Groups of closely spaced light fixtures (e.g., guard lights) are often set in a portland cement concrete (PCC) base. Arrangements are most easily constructed when the PCC base extends up to the final pavement elevation. In this case, the taxiway can be fully paved with HMA and then a slot can be sawcut for the PCC base and light fixtures. Arrangements are more difficult to construct when the PCC base does not extend up to the final pavement elevation (see Image). In this case, the PCC and fixtures must be constructed first then HMA must be paved in between the light fixtures to reach the final pavement elevation. Since the fixtures are closely spaced, there is generally not enough room to use a roller between fixtures. Therefore, fixture areas are typically compacted using hand-held plate compactors, which results in lower compaction levels and more roughness in these areas.